How to troubleshoot headlight problems -

How to troubleshoot headlight problems

The headlight bulbs themselves, the fuses that operate on the circuit to protect it from power surges, the wiring harness bringing power to the headlights, or the headlight switch, which allows the driver to switch between low and high beams, could all have failed if your car’s headlights stopped working. Your headlight faults could be caused by any of these components. Although we have a complete guide to your headlight repairs, the solution to your headlight problems can be found below: 

Step 1

Turn your headlights on. Replace any headlight bulb that isn’t working. Although the procedure for changing a headlight bulb varies by car make and model, in general, detach the wiring harness from the back of the headlight assembly, unhook the holding clip, and pull out the bulb. Replace the bulb, fasten it using the retaining clip, then plug the wiring harness back in. Recheck the headlights. If none of them turn on, move on to the next step.

Step 2

Open the fuse box in the engine compartment. Remove the fuse that controls the faulty headlight circuit. Check for discoloration on the fuse. Replace if needed and change the headlight relay. Turn on the headlights once more. If none of these work, move on to the next step.

Step 3

Connect your voltmeter’s negative lead to your car battery’s negative terminal. Connect the voltmeter’s positive lead to the wiring harness’s positive lead. The positive lead, which is commonly the red wire, receives power. Make that the wire harness is receiving current. If no current is flowing through, replace it. Turn on the headlights once more. If they still won’t switch on, move on to the next step.

Step 4

Disconnect the car battery’s negative battery cable. Remove the bezel from the steering wheel’s steering column. Remove the wiring block from the headlight switch’s back. Check for discolored connections on the wire block or headlight switch. Use a pencil eraser to carefully clean them. Replace the plug and switch on the headlights. If they still don’t function, the headlight switch may need to be replaced.

How to repair headlight wiring

How to Repair Headlight Wiring

The headlight circuit in most cars consists of four basic components: the headlight bulb, the wiring harness (which supplies power to the headlight bulb), and the fuse (which protects the circuit from power surge damage). The headlight circuit may not work if any of these basic components are damaged. You can repair or replace these components in a simple diagnostic procedure.

Step 1

Turn on your headlights and determine which is broken. Turn the headlights off. 

Step 2

With your crescent wrench, loosen the negative battery terminal screw. Remove the negative battery cable from the terminal with your fingers.

Step 3

Disconnect the electrical harness on the headlight assembly’s backside. Make that the contacts in the headlight socket and the wiring harness are clean. Look for corroding and discoloration.

Step 4

With the pencil eraser, remove the top layer of corrosion. To prevent future corrosion, apply a dab of dielectric grease to the wiring harness contacts. Re-connect the electrical harness to the headlight socket. Connect the negative battery terminal to the negative cable. Turn on the headlights once more. Move to the next step if this doesn’t work.

Step 5

Open your car’s fuse box.

Step 6

For the headlight that isn’t working, remove the fuse that controls the headlight circuit. Make sure the fuse isn’t blown. As needed, replace. Recheck the headlights. Move to the following step if the first doesn’t work.

Step 7

Disconnect the headlight wiring harness from the faulty headlight. Connect the voltmeter’s negative lead to the negative battery terminal. Connect the voltmeter’s positive lead to the headlight wiring harness’s positive wire. Current should be flowing through the positive wire. Make that the positive wire is receiving current. Replace the headlight bulb and turn on the headlights again if current is coming through the wire harness. Move to the next step if no current is flowing through the wiring harness.

Step 8

Return to the fuse box by following the headlight wiring cable. Examine the cable insulation for any tears. Unplug the battery’s negative cable if any tears are discovered. With your wire cutters, cut the cable at two points: before and after the tear. With your solder sleeve connectors and the heat gun, reconnect each wire in the cable. Remove 1/2 inch of insulation from each wire’s end. Over one of the wires, place the solder sleeve connector. Neutral to neutral, positive to positive; knot the bare leads of the relevant wire. Over the braided leads, place the solder sleeve connector. To melt the solder inside the solder sleeve connector, heat the connector. Check that the headlights are working by turning them on.



Once you are done fixing your car headlights, turn them on and check how bright they are. If the beam illuminating from the headlight lenses aren’t clear, it means you have to also restore your car’s headlight lenses. To do this, kindly buy a headlight restoration kit from your local store or online and use it to wipe your headlights regularly to get rid of oxidation. 

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